Multiple drop down menu items to populate the a separate text box...more help please

Question

Thanks to Gilad D67 for showing me how to have multiple drop down menu items appear in a separate text box. This stuff blows my mind. Is there any script I can use to make a new drop down menu item appear in the same text box, but on a new line below a previous entry. For example. I select 'cat' from my drop down menu and it appears in my text box. Now I choose 'dog' from my menu and it appears in my text box like so  'cat dog.' Is there any way I can make 'dog' go straight to a new line automatically without having to manually go into the text box and change it?
cat
dog (new selection goes straight to a new line)
Now, I don't have a clue if this is also possible, but imagine, I don't like my drop down menu selection of 'dog' and I go back into the menu and I change to 'rat' but in the text box, 'dog' still appears and 'rat' is added. Do I have to manually delete 'dog' from the text box or is there script that can do this for me.
Any assistance would be incredible. It amazes me how people know this stuff.
This is the script I have so far
(function () {
    // Do nothing if not committed
    if (event.willCommit) return;
    // Set up an array to hold the individual paragraphs of text
    var aQuotes = [3];
    // Populate the array with the paragraph text
    aQuotes[0] = "Use common singular nouns, plural nouns [plural ‘s’] and proper names to say what things are"
    aQuotes[1] = "Use numbers 1–10 to count"
    aQuotes[2] = "Use basic adjectives and colours to say what someone/something is or has"
    // Get the selected item, which is the export value of the selected combo box item
    var item = event.changeEx
    // Display the text corresponding to the selected item in the text field
    getField("Text30").value += " " + aQuotes[item];

Answer 1

You have to set the option for the text field to be multiline and then change the last line of the script to:
getField("Text30").value += "\r" + aQuotes[item];
To reset the field you can use a separate button with a Clear Form command, and then you just select this one field from the list.